Import builtin module without prefix

[MaxGyver83]

I would like to import (os) without prefix:

(import os :prefix "")

This fails because this module can't be found.

I'm aware that os is already imported but with a prefix. How can I import it without prefix?

[iacore]

You want to assign new variables. Here's how you get the names with "os/".

(->> (all-bindings) (filter |(string/has-prefix? "os/" $)))

[iacore]

You can set the current environment directly.

(set ((curenv) 'cd) (dyn 'os/cd))

[ianthehenry]

You can use set to mutate the environment, but put does the same thing with fewer parens. ¯\_(ツ)_/¯

[sogaiu]

Sorry, couldn't resist the temptation.

[MaxGyver83]

(eval-string (string "(def " (string/replace "os/" "" $) " " $ ")"))
(eval ~(def- ,(string/replace "os/" "" $) ,$))

This doesn't work:

repl:1:> (->> (all-bindings)
repl:2:(>      (filter |(string/has-prefix? "os/" $))
repl:3:(>      (map |(eval ~(def- ,(string/replace "os/" "" $) ,$))))
error: unexpected type in destruction, got "arch"
  in eval [boot.janet] (tailcall) on line 2665, column 5
  in map [boot.janet] on line 998, column 3
  in _thunk [repl] (tailcall) on line 3, column 6

Do you know what's wrong here?

[ianthehenry]

Oh, yeah, sorry -- the string/replace implicitly converts your symbol into a string and returns a string, but we need a symbol there. Using ,(symbol/slice $ 3) instead will work.

This type difference is lost when you turn the whole thing into a string -- strings and symbols have the same string representation -- but it's important in the s-expression. It's the difference between typing (def "arch" os/arch) and (def arch os/arch) at the repl -- the former is not allowed.